• Journal of Power Electronics
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• 제11권6호
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• pp.880-889
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• 2011

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g. undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.96-103
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• 2023

This paper presents a robust position tracking controller for a motor used in semiconductor equipment, utilizing the motor angle measurement. Precise position control is challenging due to the presence of uncertainties in various motor applications. The proposed controller consists of a PD (Proportional-Derivative) controller and a PIO (Proportional-Integral Observer) to estimate the system's state and equivalent disturbance compensating for the uncertainties. Since the stability alternates as the observer gain increases, we have investigated it through the closedloop root locus under the system parameters change. The analysis has showed that the inertia of the motor is the main parameter that affects it, and by adjusting the control gain appropriately, the system can be rendered to be stable even when the inertia of the motor changes. The effectiveness of the proposed control algorithm is validated through computer simulations, followed by a comparison of its performance with the results of a previous study.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.94-100
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• 2024

Recently, as interest in personal hygiene has increased due to the community spread of COVID-19 and variant viruses, fixed and potable UV germicidal equipment to sterilize indoor spaces and hand-held UV germicidal equipment to sterilize household items such as masks and mobile phones are continuously being developed and sold. However, the development and sales of the product are difficult because appropriate testing methods have not yet been established. In this situation, if an uncertified product is distributed in the market, it can cause serious harm to consumers. In this study, we investigate the photobiological risks and safety devices against UV exposure of UV germicidal equipment distributed domestically, and propose appropriate test methods for portable UV germicidal equipment based on the research results.

• Journal of Power Electronics
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• 제17권2호
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• pp.346-357
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• 2017

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

• Journal of Power Electronics
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• 제16권4호
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• pp.1513-1525
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• 2016

Rapid and accurate phase synchronization is critical for the reliable control of grid-tied inverters. However, the commonly used software phase-locked loop methods do not always satisfy the need for high-speed and accurate phase synchronization under severe grid imbalance conditions. To address this problem, this study develops a novel open-loop phase locking scheme based on a synchronous reference frame. The proposed scheme is characterized by remarkable response speed, high accuracy, and easy implementation. It comprises three functional cascaded blocks: fast orthogonal signal generation block, fast fundamental-frequency positive sequence component construction block, and fast phase calculation block. The developed virtual orthogonal signal generation method in the first block, which is characterized by noise immunity and high accuracy, can effectively avoid approximation errors and noise amplification in a wide range of sampling frequencies. In the second block, which is the foundation for achieving fast phase synchronization within 3 ms, the fundamental-frequency positive sequence components of unsymmetrical grid voltages can be achieved with the developed orthogonal signal construction strategy and the symmetrical component method. The real-time grid phase can be consequently obtained in the third block, which is free from self-tuning closed-loop control and thus improves the dynamic performance of the proposed scheme. The proposed scheme is adaptive to severe unsymmetrical grid voltages with sudden changes in magnitude, phase, and/or frequency. Moreover, this scheme is able to eliminate phase errors induced by harmonics and random noise. The validity and utility of the proposed scheme are verified by the experimental results.

• 한국정보통신학회논문지
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• 제20권6호
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• pp.1142-1147
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• 2016

최근 다양한 분야에 걸쳐 ICT 기술을 융합하여 지능적인 서비스를 제공하는 IoT에 대한 다양한 연구가 진행되고 있다. 특히 독일의 'Industry 4.0'의 등장으로 제조 산업에 ICT를 융합하여 생산능력을 극대화 하는 industrial IoT의 중요성이 강조되고 있다. 이에 국내에서도 industrial IoT의 근간이 되는 스마트 팩토리 보급을 위한 다양한 노력이 진행 중이다. 그러나 현재의 스마트 팩토리 시스템은 장비의 임베디드 시스템에 선언된 데이터를 통해 설비를 제어하며, 다수의 설비가 배치되어 있는 환경에 대처하기 어렵다. 본 논문에서는 industrial IoT를 위해 장비의 변수 정보를 DB화하여 장비를 제어하는 데이터베이스 접근 기반 장비 제어 시스템을 제안한다. 제안하는 시스템을 다양한 변수가 존재하는 사출 시스템에 적용하여 데이터베이스의 수정으로 다수의 장비를 제어하는데 효율적임을 확인하였다.

• 한국정보통신학회논문지
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• 제14권6호
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• pp.1447-1452
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• 2010

Ubiquitous 사회에서 기본 인프라를 구축하는 전력 공급망과 전력기기의 안전은 중요하다. u-City의 재난을 방지하기 위하여 u-IT전력기기의 모듈별 성능평가와 보안은 u-City 안전을 위해 꼭 필요하다. 본 논문에서는 u-IT전력기기의 모듈에 온도센서, 습도센서, 화재센서들을 탑재한 수배전반, 홈 분전반, Home Network Wall-Pad, 차단기, MPNP 블랙박스, 아크 검출기, 아크 안전기, 아울렛의 모듈별 성능평가 방안과 방법 및 보안방법을 연구한다. u-IT전력기기들은 센서의 정보들을 전달 및 분석하여 위험성을 사전 예방하여 안전성을 확보하고, 접근제어, 인증 등 보안대책으로 u-IT 전기안전통합관리시스템의 보안성을 강화시켜, 안전성과 보안성을 갖춘 u-City건설과 운영에 기여하게 될 것이다.

• 전기학회논문지P
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• 제64권4호
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• pp.251-255
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• 2015

Chiller system plays an important role of maintaining room temperature constantly by supplying chilled water to Heating, Ventilating and Air Conditioning(HVAC)or area room cooler equipment during plant normal operation or accident condition. Chiller failures are one of the most frequently occurring equipment failures. If the types of chiller failures are analyzed and grouped thoroughly, it would be helpful to make chiller maintenance strategy at the plants. That would enhance equipment reliability of chiller in the end. In this paper, chiller failure data during three years were analyzed and categorized by specific failure code. In addition, the various proposals to improve equipment reliability of chiller were suggested such as Preventive Maintenance Optimization(PMO) strategy and performance monitoring reinforcement and so on.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.370-373
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• 2004

The inside and outside of the country utilities considered that they focused energy and economic aspect for short-term in new environment change of restructure. but it need service reliability preservation and improvement countermeasure, that is no to use existent estimation method for reliability preservation. therefore, analyze the equipment failure rate for suitable reliability preservation through equipment failure rate analysis of power distribution r system and evaluated equipment that is composing power distribution system by the failure rate. This paper estimated failure causes and the TVFR(Time Varying Failure Rate) for main equipment that is composing power distribution system using Weibull distribution.

• 전기학회논문지P
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• 제58권1호
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• pp.90-94
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• 2009

The inundation of substation and ground power equipment breaks out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. For diminishing flood damage of electrical equipment in the root, flood protection system which is used the basic frame of Pad transformer is developed using pneumatic pressure. This system is established on pressure generator equipment and sensor of flooded level operates at flooding occurrence and is maintained a shutting tightly structure. The system is able to protect indraft water in Pad Transformer and supply the electricity at emergency(flooding). And we tested safety for insulation resistance at flooding and applying an electrical current. We estimate that loss cost which is caused by with flooding and the power failure will be diminished if it is addition to advances the reliability evaluation by setting an example.